Immobilization of proteins on solid surfaces plays an important role in all the fields of modern biology. Two approaches are used in the immobilization of proteins: a random and an oriented mode of binding to solid matrices. In this note, we show that there is not much difference in using either mode of immobilization, since proteins usually bind to a matrix through only one or two bonds. This is demonstrated by the attachment of several proteins to CNBr-activated Sepharose through their lysines and the consequent conversion of those lysines to homoarginine upon treatment with ammonium hydroxide.